Pen size LED inspection lamp for detecting fluorescent material

ABSTRACT

A pen-size inspection lamp for detecting fluorescent leak detection materials in hard-to-reach areas. The inspection lamp includes a housing, an extendible handle, at least one LED and a mirror assembly. The mirror assembly includes a mirror, a clip for attaching the mirror to the housing, and an arm extending between the clip and the mirror with a hinge connection for rotating the mirror to different reflection angles with respect to the LED.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority from U.S.application Ser. No. 09/899,796, filed Jul. 5, 2001.

FIELD OF THE INVENTION

[0002] The invention relates to the general field of inspection lampsutilized for detection of fluorescent materials.

BACKGROUND OF THE INVENTION

[0003] Leak detection and surface flaw non-destructive testingtechniques often use fluorescent dye additives or fluorescentpenetrants. These techniques rely upon the unique physical property ofvarious materials to fluoresce when excited by certain wavelengths oflight.

[0004] Fluorescence is generally understood to be a property thatenables some materials to absorb light energy and to radiate visiblelight at a longer wavelength than the absorbed light. According togenerally accepted theory, electrons in fluorescent materials areexcited upon being illuminated by light energy of a specific absorptionband wavelength, and emit light energy in a longer wavelength responseband as the electrons return to the unexcited or ground state. Thespecific excitation and response wavelengths are characteristics of theparticular fluorescent materials.

[0005] The apparent brightness of a fluorescent material's luminescenceis dependent on the wavelength and the intensity of the incidentradiation. The excitation band generally has one or more peakwavelengths that will produce a greater response than incident light ofthe same intensity at an off-peak wavelength. Thus, a fluorescentmaterial which has an excitation peak at a specific wavelength mayexhibit a much reduced luminescence as the wavelength of incident lightdeviates from the excitation peak, and will lose the ability tofluoresce when the incident light does not provide enough energy withinthe excitation range.

[0006] For example, two commonly used fluorescent leak detection dyesare perylene-based fluorescent compounds and naphthalimide-basedfluorescent compounds. Perylene dyes produce a yellow fluorescentresponse when exposed to incident radiation which includes the UV-Awavelength band of about 315 nm to about 400 nm, with a strong peakbetween about 340 to 375 nm. Naphthalimide dyes fluoresce green whenexposed to incident radiation of visible violet/blue light in a rangefrom about 400 nm to about 480 nm.

[0007] A fluorescent response is more visible when the intensity ofother visible light is reduced, so that the fluorescent response is notmasked or washed-out by other light. The various UV-A or Violet/Blueinspection lamps use several types of light sources and filtering toproduce a light output in the excitation bands with little or no outputlight in the fluorescent response band. For example, a lamp having ahigh intensity incandescent light source with a narrow band UV (360-370nm) absorption filter will emit light energy concentrated around theexcitation peak of a perylene dye additive. An inspection lamp with awider band UV/BLUE absorption filter centered at about 400 nm providesoutput in the UVA and visible violet/blue range, with the greatestintensity centered in the excitation band of a common naphthalimide dyecompound. In the absorption filter lamps, however, the larger portion oflight energy in the visible and infrared wavelengths is absorbed as heatin the filter.

[0008] A more efficient inspection lamp uses thin-film dichroicreflectance filter. A dichroic filter can be tailored to reflect backinto the lamp only the range of visible wavelengths outside of thechosen excitation band, while passing the other wavelengths. Because theemitted light is not converted to heat in the dichroic filter, the lampcan be made considerably more compact than the lamps with absorptionfilters.

[0009] All of the above-described prior lamps use a broad spectrum lightsource, and thus require some type of filtering, whether absorption ordichroic, to transmit light in an excitation band while restrictinglight output in the visible fluorescent response band. In the presentinvention, however, the inspection lamp uses the narrow bandelectroluminescence of solid state lamps, specifically light-emittingdiodes (hereinafter referred to as “LEDs” ) with glass envelopes thatrefract light to the tip of the envelope. LEDs have been known for manyyears, but until recent developments it has been difficult to obtainsufficiently high levels of luminous flux as would be required for aninspection lamp. This problem was particularly acute for LEDs emittingin the blue to UV bands, which produced much less lumens per watt thanthe red, yellow and green emitting LEDs. [See, Lighting Handbook, 8^(th)edition, Illuminating Engineers Society of North America, Chapter 6,FIG. 6.68(f)].

[0010] Recent developments in nitride semiconductor materials,particularly gallium nitride (GaN) based epitaxal structures, haveprovided more efficient LEDs that can produce sufficient lumens for aninspection lamp in the UV 360-390 nm range. For example, a GaNelectroluminescent device as described in U.S. Pat. No. 5,898,185 has anemission peak at 380 nm. An LED emitting in the 360 nm-390 nm rangewould make a useful light source for detection of a perylene dye.

[0011] GaN alloys can produce other useful emission bands. The samepatent describes a commercial GaInAlN LED that emits blue light at 460nm. The light emission wavelengths of GaN LEDs can also be altered byphosphor films if desired. As described in the specification of the U.S.Pat. No. 5,898,185 patent, these GaN-based LEDs have high efficiencies,typically in the energy emitted/power-in range of 10%.

[0012] The invention uses these LED light sources in the form of a LEDbulb in which the glass lens capsule directs light to the rounded tip ofthe capsule. This causes a narrow high intensity focus at the tip and adiverging beam emanating from the tip. The effect is having a highestlight intensity at the capsule tip and a rapidly decreasing intensity asdistance from the tip increases. Thus, while the intensity at closedistances may be sufficient to excite a strong response from afluorescent dye, the intensity at longer distances may not be enough toproduce the fluorescent response.

[0013] An LED inspection lamp can be very small, in fact, it can be thesize of a pen light powered by AAAA sized batteries. A current LED penlight, the STYLUS™ model with an “Ice Blue” emitting LED is only 0.38inches in diameter and 6.60 inches in length and operates on three AAAAbatteries with a run time of over 10 hours, yet it has sufficient bluelight output to cause a fluorescent response in a naphthalimide-basedleak detection additive from a distance of 18 inches in dark conditions.Even in daylight conditions, it can excite a naphthalimide dye to abright response at one to six inches.

[0014] Although the narrow shape of the LED pen light is helpful inallowing the LED capsule to be inserted into narrow areas close to asuspected leak site, it is still restricted by its length. Furthermore,the metal handle and battery housing is inflexible. Both the shortlength and inflexibility can make it difficult or impossible to reachareas of potential leak sites, such as lines and connectors in thecircuit of an automobile air conditioner.

[0015] It would therefore be useful to provide an LED lamp that has ahigh intensity focus at the tip as well as an extendible handle so thatthe lamp may be inserted deeply into tight areas to bring the tip of theLED capsule close to the potential leak site to be investigated forfluorescent material. An extendible handle may alternatively be flexibleto aid in insertion around obstructions. An alternative embodiment lampmay have two or more different color LEDs, such as violet and blue,which may be selectively used to detect more than one type offluorescent material, or may have an LED and a white light bulb toselect between general illumination and fluorescent detection. An LEDlamp with an extendible handle may also have a mirror attached to permitinspect under or around an obstruction.

SUMMARY OF THE INVENTION

[0016] In accordance with the present invention, there is provided aninspection lamp for detecting fluorescent materials. The inspection lampincludes a housing, an extendible handle, and at least one LED, and mayinclude a mirror.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For the purpose of illustrating the invention, there is shown inthe drawings a form which is currently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

[0018]FIG. 1 is an isometric view of an embodiment of the inspectionlamp in accordance with the present invention.

[0019]FIG. 2 is an exploded isometric view of an embodiment of theinspection lamp in accordance with the present invention.

[0020]FIG. 3 is an isometric view of an embodiment of the inspectionlamp in accordance with the present invention.

[0021]FIG. 4 is an illustration of a human being with an embodiment ofthe inspection lamp in his shirt pocket.

[0022]FIG. 5A is a side elevation view of an embodiment of theinspection lamp in accordance with the present invention.

[0023]FIG. 5B is an isometric view of the lamp housing of an embodimentof the inspection lamp in accordance with the present invention.

[0024]FIG. 6A is a side elevation view of an embodiment of theinspection lamp in which the lamp is in the unextended position inaccordance with the present invention.

[0025]FIG. 6B is a side elevation view of an embodiment of theinspection lamp in which the lamp is extended in accordance with thepresent invention.

[0026]FIG. 7A is a side elevation view of an embodiment of theinspection lamp in which the lamp is in the unextended position inaccordance with the present invention.

[0027]FIG. 7B is a side elevation view of an embodiment of theinspection lamp in which the lamp is extended in accordance with thepresent invention.

[0028]FIG. 7C is an isometric view of the lamp housing of an embodimentof the inspection lamp in accordance with the present invention.

[0029]FIG. 8 is an isometric view of an embodiment of the inspectionlamp in which the inspection lamp includes a telescoping handle.

[0030]FIG. 9 is an isometric view of an embodiment of the inspectionlamp that includes an attached mirror.

[0031]FIG. 10 is an isometric view of the embodiment in FIG. 9 showing atelescoping handle and the light emitted from the LED reflected in themirror.

DESCRIPTION OF THE INVENTION

[0032] FIGS. 1-4 show an embodiment of an inspection lamp 10 inaccordance with the invention. This embodiment of inspection lamp 10includes an LED pen light 12 having an aluminum housing 14. In thisembodiment, shown in FIG. 2, a rear end of the housing is threaded whilethe front end includes an aperture for receiving a glass lens capsule16. The housing 14 is adapted to enclose the LED pen light's batteries,switch contacts and light source. The pen light 12 uses a blue LED asits light source. The glass lens capsule 16 of the LED extends outthrough the front end of the housing. An example of a suitablecommercially available LED pen light of this type is the STYLUS3 “ICEBLUE” penlight by Streamlight®.

[0033] The bottom of the pen light housing 14 has a screw cap 18 thatalso serves as an ON/OFF switch by pressing the batteries into anelectrical connection, either by tightening the screw cap or by pressinga momentary switch at the back of the cap.

[0034] A hollow extendible handle 20 is adapted to slidingly engagearound the housing 14 of the LED pen light. The top end of theextendible handle is adapted to receive a locking mechanism 24 forlocking the handle in a desired position relative to the housing, ineffect extending the handle of the inspection lamp 10 to a desiredlength. In this embodiment, the top end of the handle is threaded andslotted, while the locking mechanism is a threaded collar. When thecollar 24 is tightened to the bottom of the threads, it compresses theslotted tip of the handle and presses it against the pen light housingto keep the pen light from sliding within the handle. A stop ring 22 isprovided around the pen light housing to prevent the collar fromslipping off the front end of the pen light.

[0035] In FIG. 1, the inspection lamp is shown locked in a fullyretracted position. FIG. 3 shows the same lamp locked in a fullyextended position. FIG. 4 shows the inspection lamp carried as a penlight inside a shirt pocket so as to illustrate the lamp's relativesize.

[0036] The light from the LED is directed through the rounded tip of theglass lens capsule. Thus, the emitted light beam has its highest lightintensity in a narrow beam at the tip of the glass capsule 16, and thebeam diverges as distance from the tip increases.

[0037] In FIGS. 5A and 5B, an alternative embodiment inspection lamp 26uses three LEDs 28 inside a lamp housing 30. The lamp housing 30 isattached to an extendible handle 26 having an upper flexible portion 32and a lower rigid portion 36 of the inspection lamp. The upper flexibleportion 32 includes a hollow cavity and can be adjusted and extended asdesired. The upper flexible portion 32 can be folded onto the lowerrigid portion 36 to shorten the length of the inspection lamp.

[0038] The underside of the lamp housing 34 includes electrical contacts38 to connect the LEDs 28 to a conductor wire 40. The wire 40 extendsdownward from the electrical contact 38 through the upper flexibleportion 32 to connect with the batteries 37. The lower rigid portion 36includes a removable cap 42. The removable cap 42 includes a metalliccoil for completing the circuit in the typical fashion to power the LEDs28.

[0039]FIG. 5B shows a closer view of the lamp housing 30. The top sideof the lamp housing includes a rotatable cover 44 with an aperturesuitable for only one LED for selectively blocking the light from two ofthe LEDs, so that only the light from one LED is emitted from theinspection lamp at any one time. The lamp housing 30 may containdifferent LEDs 28 and may also include an incandescent lamp or othersuitable source of white light.

[0040] For example, the lamp may contain three LEDs, one in each ofultraviolet, blue, and green. Depending on the fluorescent dye beingused, the cover can be rotated so that only the appropriate LED isemitted by the inspection lamp. For instance, if a perylene-basedfluorescent compound is being used, the ultraviolet LED may be selected.When using a naphthalimide-based fluorescent compound, the blue LED maybe selected.

[0041] Shown in FIGS. 6A and 6B is another embodiment where the pen-sizeinspection lamp has an extendible handle 46 which is at least partflexible. An upper flexible portion 48 is slidably engaged with thelower rigid portion 50. The upper flexible portion 48 has an innerdiameter greater than the outer diameter of the lower rigid portion 50.FIG. 6A shows the inspection lamp in a non-flexed and non-extendedposition. FIG. 6B shows the inspection lamp fully extended and partiallyflexed.

[0042]FIGS. 7A, 7B, and 7C show another embodiment of the presentinvention, in which the inspection lamp has four LEDs 54 attached to alamp housing 56. An incandescent lamp or other source of white light maysubstituted for one of the LEDs. The lamp housing is rotatably attachedto an upper portion 58 of an extendible handle 52. The extendible handle52 comprises the upper portion 58 and a lower portion 60. The upperportion 58 is slidably engaged with the lower portion 60. The outerdiameter of the upper portion 58 is less than the inner diameter of thelower portion 60. The upper portion 58 and lower portion 60 include ahollow cavity as shown in FIGS. 7A and 7B. In a preferred embodiment,the hollow cavity of the upper portion 58 contains a power source. Inthe same embodiment, the power source is an internal power sourcecomprising at least one battery 64.

[0043] The underside of the lamp housing 56 includes a plurality ofelectrical contacts 62. The number of electrical contacts 62 located atthe underside of the lamp housing 56 corresponds to the number of LEDsand sources of white light 54 attached to the lamp housing 56. As notedearlier, when working with leak detection dyes, certain LEDs work mostefficiently in conjunction with certain fluorescent compounds. In oneembodiment, three LEDs, ultraviolet, blue, and green, and one source ofwhite light are attached to the lamp housing. In order to selectivelyilluminate a single LED or source of white light, the lamp housing 56 isrotated so as to cause the electrical contact of the desired LED orwhite light to contact the inspection lamp's source of power. Forinstance, if the green LED is to be emitted by the inspection lamp, thelamp housing 56 is rotated so as to cause the green LED's electricalcontact to connect with the power source.

[0044] The embodiment of the present invention shown in FIGS. 7A and 7Bmay be extended to illuminate hard-to-reach areas. FIG. 7B shows theinspection lamp fully extended.

[0045] Referring now to FIG. 8, another embodiment of the presentinvention is shown in which the inspection lamp 66 includes anextendible handle 67 and a removable LED lamp assembly 72. In thisembodiment, the extendible handle 67 is comprised of a plurality ofslidingly engaged cylinders 70 of sequentially reduced diameter tofacilitate the handle's ability to extend and contract in a telescopingmanner. The telescoping handle 67 may be comprised of any number ofcylinders and those cylinders may be of any size or shape. For instance,the circular section cylinders may be replaced with hollow squarecylinders. In FIG. 8, the handle is shown in an extended position.

[0046] In one embodiment of the inspection lamp 66 shown in FIG. 8,there is a battery housing 68 opposite the telescoping handle 67. Thebattery housing 68 may include controls 69 for connecting the LED lampassembly 72 to at least one battery and to have a threaded top (notshown) for releasably engaging a screw cap 71. The battery housing 68 isconfigured to accept coin-sized batteries (not shown) to provideelectrical power to the LED lamp assembly 72. The LED lamp assembly 72is releasably attached to the screw cap 71. In the depicted embodiment,the LED lamp assembly 72 may be locked in place with a lockingmechanism, an example of which is shown in FIG. 8, numeral 73. Thelocking device 73 shown in FIG. 8 is simply shown as an example; thoseskilled in the art will realize that many arrangements capable ofreleasably locking the LED lamp assembly 72 to the screw cap 71 could beused.

[0047] In a preferred embodiment, the LED lamp assembly 72 includes anLED 74 with a wavelength band having a peak intensity below about 500nm. It is important to note however, that the LED lamp assemblies 72 areinterchangeable, and thus the lamp 66 may be configured with an LEDhaving any wavelength band. Therefore, if it is desirable to utilize anLED of a particular color, the user may simply replace the LED lampassembly 72 with an LED lamp assembly 72 having the color of choice. Forinstance, a user using the inspection lamp 66 with a LED lamp assembly72 having a blue LED may find it desirable to use a LED lamp assembly 72having a green LED. If so, the user may simply remove the LED lampassembly 72 having a blue LED and replace it with a LED lamp assembly 72having a green LED.

[0048] In other embodiments, where the LED lamp assembly 72 may includetwo or more LEDs, it is preferable if at least one LED has a wavelengthband with a peak intensity below about 500 nm. In such an embodiment,the controls 69 are adapted to selectively illuminate at least one LED,as desired.

[0049] In a preferred embodiment, there is a hinge 75 located betweenthe handle 70 and the housing 68, as shown in FIG. 8. In otherembodiments, where a hinge is not present, housing 68 is simply attachedto the telescoping handle 70.

[0050] It is important to note that the various forms of extendiblehandles as well as the manner in which the various embodiments are ableto emit a single LED or white light and are able to extend and flex iscompletely interchangeable. For example, the lamp housing 30 and cover44 used for selectively emitting a single LED as shown in FIGS. 5A and5B may be utilized with the upper 58 and lower 60 cylindrical portionsshown in FIGS. 7A and 7B.

[0051] In other embodiments, aspects of the handle may includealternative means for extending the inspection lamp from a shorterconfiguration to a longer configuration. Such means may include, forexample, a spring and release mechanism for causing the inspection lampto quickly extend by activating the release of a spring-type mechanismor other device capable of causing the inspection lamp to quicklyextend. A means for extending the inspection lamp may also be configuredsimilar in operation to a typical jack knife that is folded in half andlocked when not in use. Such a configuration could include a hinge,ball-joint or other suitable element for causing the lamp to becollapsed approximately in half. A configuration could also include alocking mechanism so that the lamp is locked into place when collapsedor folded, as well as a release mechanism for releasing the lock. Therelease could be employed with or without a spring-type mechanism.

[0052]FIGS. 9 and 10 show an embodiment of the invention in which amirror assembly 200 is attached to the pen size LED lamp of FIG. 8. Themirror assembly comprises a mirror 202, a clip 204 for attaching themirror to the LED lamp assembly, an arm 206 extending from the clip tothe mirror, and a hinge 208 which allows the mirror to be rotated todifferent reflection angles with respect to the LED assembly. The mirrorassembly is clipped onto the LED assembly 172 at or near the batteryhousing 168. The clip allows the mirror assembly to be removed from thelamp, and to be attached to the lamp with the arm lying along the lampfor storage or extending in front of the lamp for use in leak detection.

[0053] A similar mirror assembly may be attached to others of thevarious embodiments of the LED lamp. For example, in the embodimentshown in FIGS. 1 to 4, the mirror assembly may be clipped at or nearstop ring 22. For the embodiment shown in FIGS. 5 and 6, the mirrorassembly may be attached to the flexible portion 32, 48 of extendiblehandle 26, 52 at or near the LED lamp housing 30. For the embodimentshown in FIG. 7, the mirror assembly may be attached at or near handle64 after extension and close to lamp housing 56.

[0054] Adding the mirror assembly to the lamp increases the ability todetect fluorescent material in hard-to-see areas such as around cornersor underside surfaces. As shown in FIG. 10, the user may rotate themirror so that it reflects the emitted light 210 from the LEDs at anangle set by rotating the mirror on the hinge. The user may thenposition the mirror to reflect onto a location that cannot beilluminated directly by the LED so that the location may be viewed inthe mirror. If fluorescent leak detection material is present,illumination by the LED light reflected off the mirror will produce afluorescent response and indicate a leak at the location. The mirrorwill be particularly useful in detecting leaks that occur on theunderside or out-of-view portion of air conditioner components, hoses orfittings that cannot be easily accessed for direct observation.

[0055] The invention may also be embodied in other specific formswithout departing from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification, as indicating the scope of theinvention.

What is claimed is:
 1. An inspection lamp for detecting refrigerantleaks from air-conditioning systems through illumination of fluorescentmaterial added to the refrigerant, the inspection lamp comprising an LEDpen light having an extendible handle and an LED lamp housing at one endof the handle, the lamp housing containing an LED, said inspection lampfurther comprising; a mirror assembly comprising a mirror; a clip forattaching the mirror to the lamp at or near the LED lamp housing; and anarm extending between the clip and the mirror, said arm having a hingeconnection with the mirror for rotating the mirror to differentreflection angles with respect to the LED.
 2. An inspection lamp as inclaim 1, wherein the LED emits light within a wavelength band belowabout 500 nm.
 3. An inspection lamp as in claim 1, wherein the handlehas an upper flexible portion attached to the lamp housing and a lowerportion, wherein the flexible portion may be bent to fit intohard-to-reach areas of air-conditioning systems.
 4. An inspection lampas in claim 3, wherein the LED emits light within a wavelength bandbelow about 500 nm.
 5. An inspection lamp as in claim 1, furthercomprising: the handle having a grip section and telescoping sectionsadapted to be pulled out to extend the handle and pushed in to retractthe handle; and a battery housing containing a battery, the batteryhousing being attached at one end thereof to the telescoping sectionthat is furthest from the grip section when the handle is extended. 6.An LED inspection lamp for detecting refrigerant leaks fromair-conditioning systems through illumination of fluorescent materialsadded to the refrigerant and lubricating oil, said inspection lampcomprising: an extendable and retractable handle having a grip sectionand telescoping sections adapted to be pulled out to extend the handleand pushed in to retract the handle, a battery housing containing abattery, the battery housing being attached at one end thereof to thetelescoping section that is furthest from the grip section when thehandle is extended; an LED lamp assembly connected to the batteryhousing and containing an LED that emits light within a wavelength bandbelow about 500 nm; and a mirror assembly having a mirror, a clip forattaching the mirror to the battery housing, and an arm extendingbetween the clip and the mirror, said arm having a hinge connection withthe mirror for rotating the mirror to different reflection angles withrespect to the LED.